Well, no, you don't. The reason is that diffraction, at the pixel level, also begins to act as a type of AA filter.

Assuming lenses of equal aperture/sharpness ... right?

Yes. In fact, diffraction is but one of many sources of blur (such as lens aberrations and motion), so lens aberrations serve the same role as diffraction, more so at the wide end of the aperture range, of course.